Biden is aiming to build an effective, bipartisan Defense Department leadership team, said one former Trump Pentagon official. The Biden team will in the coming weeks be reaching out to more former officials who were appointed by Mattis to talk about the transition and potentially serving, the person said.

The team is also seeking the former officials’ help because they don’t expect current Pentagon leadership to be cooperative or particularly knowledgeable, the former official said.

Since early this year, the White House has been purging Pentagon officials who were deemed insufficiently loyal to the White House and installed those who can be trusted to carry out the president’s wishes. On Monday, Trump fired Defense Secretary Mark Esper, and a day later three more top officials were replaced by loyalists.